Some 20 U.S. soldiers were to patrol a riverbed in the dead of night, camp until morning, and provide backup to Afghan troops and their Canadian mentors in a clearing operation in Chahar Bagh village, an insurgent hotbed on the outskirts of Kandahar City.

Less than 12 hours later, seven of the soldiers and their Afghan interpreter would be dead, killed by a massive homemade bomb buried deep under pebbles along the dried-out riverbed.

The attack illustrates how a more aggressive U.S. military strategy of going into Taliban strongholds risks mounting casualties as President Barack Obama weighs whether to send thousands more troops to Afghanistan. The initial operation this week passed without incident. Around 200 Afghan soldiers and their Canadian trainers pushed through the village of mud houses surrounded by lush pomegranate orchards. A handful of men were arrested for later questioning.

The U.S. soldiers were not needed.

"What are you going to write about? This is some boring ass mission," one 1st Platoon soldier joked with a reporter as the sun rose behind a cragged mountain towering over the village.

The soldiers -- small groups from three platoons of Charlie Company, 1st Battalion 17th Infantry Regiment Stryker Brigade -- had pushed out from their base at around midnight. Not far from Chahar Bagh village, they dismounted from their armored Stryker vehicles and continued on foot.

Setting up in the riverbed alongside the village, the soldiers kept watch and waited. As the sun rose across the river valley, they jibed with each other and talked about life back home.

By mid-morning, the operation was over. Three Stryker vehicles rumbled toward 2nd Platoon men waiting further down the riverbed to bring them back to base.

As the vehicles returned with the soldiers on board, a huge explosion sent rocks and sand flying high into the air. The first Stryker had hit a massive IED or improvised explosive device, flipping the 20 metric tons vehicle onto its side.

The thick armored plate beneath the Stryker had been blown straight through the floor and the roof. Pieces of metal and debris lay strewn around the wreckage.

Minutes earlier, 1st Platoon soldiers had set off on foot, passing right over the site of the bomb, to meet their own waiting vehicles. As they mounted their Strykers, less than 400 meters away, the explosion tore through the air.

"Oh s**t! Get in! Get in!" yelled 1st Platoon Sergeant First Class Kelekolio Paresa to his soldiers and accompanying reporters as the men scrambled into the vehicles.

"I got, I got, seven KIA (killed in action) and an Afghan interpreter KIA!" a broken voice came across the radio.

"S**t, we gotta go back and help!" shouted Paresa. The 1st Platoon Strykers turned around and raced back. As they reached the scene, gunfire broke out. Insurgents, laying in wait, were firing at the Strykers from orchards next to the village.

Seconds later, the deafening sound of gunfire burst through the air as the Strykers returned fire. Empty shell casings rained down inside the vehicle, bouncing off the floor.

"Open the ramp!" shouted Paresa. Soldiers poured out of the Stryker, firing a hail of bullets and grenades toward the oncoming gunfire.

It had carried nine men. Seven soldiers and their Afghan interpreter were killed instantly. Their bodies, ripped apart in the blast, lay scattered around the wreckage. The soldiers lifted the dead onto stretchers to be picked up by a helicopter. Only the driver survived.

"Thank God we were on foot. We walked right over that IED. Twice! That triggerman was waiting for the Stryker," said Paresa later.

The men from 1st Platoon had walked across the site of the bomb and had camped no more than 50 meters away.

A command wire, used to activate the bomb, was traced some 100 meters away behind a low stone wall. An insurgent had most likely been behind the wall, waiting for a Stryker to pass full of soldiers before he detonated the bomb, the soldiers said.

They estimated the size of bomb at 600-900 kg (1,300-2,000 pounds). It was the largest IED any of the soldiers had ever experienced, in Iraq or Afghanistan.

The Stryker Brigade deployed to Afghanistan in July as part of a troop drive ordered by Obama to quell a strengthening insurgency. For the past few months, the Strykers have been trying to clear insurgents from villages they say are used as staging posts for attacks inside Kandahar City.

The militants, preempting the soldiers' arrival, have laid dozens of bombs in their path. The Strykers have suffered a high rate of casualties.

In all, the Brigade has lost more than 30 soldiers, 20 of those from 1st Battalion and 10 of those from Charlie Company. More than 40 have been wounded. IEDs, the Taliban's weapon of choice, have killed nearly 240 foreign soldiers this year alone.

"That was my best friend. We were together for two years. I just waved to him," said Specialist Nicholas Saucier, speaking about one of the dead.

"I'm sick of this s**t! Guys are getting killed every week," he said, tears welling up as he looked back at the wreckage.

Other soldiers took a more philosophical view.

"These guys are great. Even after all this, after picking up their buddies' dead body parts, they'll soldier on. They dug deep. And in a couple days they'll get back on their horse and do what they have to do," said Staff Sergeant Jason Hughes.

(Editing by Jerry Norton and Dean Yates)

Next In World News

SEOUL South Korean lawmakers voted overwhelmingly on Friday to impeach President Park Geun-hye over an influence-peddling scandal, setting the stage for her to become the country's first elected leader to be expelled from office in disgrace.

ALEPPO, Syria/BEIRUT The Syrian army pressed an offensive in Aleppo on Friday with ground fighting and air strikes in an operation to retake all of the city's besieged rebel-held east that would bring victory in the civil war closer for President Bashar al-Assad.

BAGHDAD Iraqi forces captured a neighborhood in east Mosul on Friday, pushing deeper to the heart of Islamic State's Iraq stronghold and destroying three sites where it produced car bombs used in waves of suicide attacks, the campaign's commander said.

Reuters is the news and media division of Thomson Reuters. Thomson Reuters is the world's largest international multimedia news agency, providing investing news, world news, business news, technology news, headline news, small business news, news alerts, personal finance, stock market, and mutual funds information available on Reuters.com, video, mobile, and interactive television platforms. Learn more about Thomson Reuters products: